Self expanding bifurcated endovascular prosthesis

ABSTRACT

Disclosed is a bifurcated tubular endoluminal vascular prosthesis, useful in treating, for example, an abdominal aortic aneurysm. The prosthesis comprises a self expandable wire support structure surrounded at least in part by a flexible tubular membrane. A delivery catheter and methods are also disclosed.

PRIORITY INFORMATION

This Application is a continuation of U.S. patent application Ser. No.11/417,883, filed on May 3, 2006, now U.S. Pat. No. 7,892,277, which isa continuation of U.S. patent application Ser. No. 10/119,525, filed onApr. 8, 2002, now U.S. Pat. No. 7,520,895, which is a continuation ofU.S. patent application Ser. No. 09/100,481, filed Jun. 19, 1998, nowabandoned, the entire contents of these applications being herebyincorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates to endoluminal repair of a vessel, and, inparticular, repair of a bifurcation aneurysm such as at the iliacbifurcation of the abdominal aorta.

Endoluminal repair or exclusion of aortic aneurysms has been performedfor the past several years. The goal of endoluminal aortic aneurysmexclusion has been to correct this life threatening disease in aminimally invasive manner in order to effectuate a patient's quick andcomplete recovery. Various vascular grafts exist in the prior art whichhave been used to exclude aortic aneurysms. These prior art grafts havemet varying degrees of success.

Initially, straight tube grafts were used in the infrarenal abdominalaorta to exclude the aneurysmal sac from the blood stream therebyresulting in the weakened aortic wall being protected by the graftmaterial. These straight tube grafts were at first unsupported meaningthat they employed stents at their proximal and distal ends to anchorthe proximal and distal ends of the graft to the healthy portions of theaorta thereby leaving a midsection of the graft or prosthesis that didnot have any internal support. Although this type of graft at firstappeared to correct the aortic aneurysm, it met with many failures. Theunsupported nature of its midsection allowed the graft to migratedistally as well as exhibit significant proximal leakage due to theenlargement of the aorta without adaptation of the graft, such asenlargement of the graft, to accommodate the change in diameter of theaorta.

Later, technical improvements in stent design led to “self-expanding”stents. In addition, later improvements produced “Nitinol” stents whichhad a “memory” that was capable of expanding to a predetermined size.Coincidentally, graft designers began to develop bifurcated graftshaving limbs which extended into the iliac arteries. The development ofbifurcated grafts allowed for the treatment of more complex aneurysms.With the advent of bifurcated grafts, the need for at least a onecentimeter neck from the distal aspect of the aneurysmal sac to theiliac bifurcation in order to treat the aneurysm with an endoluminalgraft was no longer needed. However, proximal necks of at least 0.5 to 1centimeter distance from the renal arteries to the most proximal aspectof the aneurysm are still generally required.

Many bifurcated grafts are of a two-piece design. The two-piece designsrequire the insertion of a contralateral limb through a separate accesssite. These types of grafts are complex to deploy and have the potentialfor leakage at the connection site of the two limbs of the graft.

One piece bifurcated grafts are also well known in the art. For example,U.S. Pat. No. 2,845,959 discloses a one piece seamless woven textilebifurcated tube for use as an artificial artery. Yarns of varyingmaterials can be used to weave the bifurcated graft including nylon andplastic yarns. U.S. Pat. Nos. 3,096,560 and 3,029,9819 issued to Liebigand Starks, respectively, disclose woven one piece bifurcated graftswhich are constructed by performing specific types of winding andweaving about a smooth bifurcated mandrel.

U.S. Pat. No. 4,497,074 describes a one piece bifurcated graft which ismade from a preformed support in the shape of the bifurcated graft. In afirst stage, a gel enabling a surface state close to that of theliquid-air interface to be obtained at the gel-air interface isdeposited by dipping or coating the preform with a sol which is allowedto cool. A hardenable flexible material such as a silicone elastomer isapplied by dipping or spraying the material on the mold in a secondstage. Finally, after hardening of the material, the prosthesis isremoved from the mold. In U.S. Pat. No. 4,816,028 issued to Kapadia etal., there is shown a one piece woven bifurcated vascular graft having aplurality of warp threads running in the axial direction and a pluralityof weft threads running in the transverse direction. Further, U.S. Pat.No. 5,108,424 issued to Hoffman, Jr. et al. discloses a one piecebifurcated collagen-impregnated dacron graft. The bifurcated graftincludes a porous synthetic vascular graft substrate formed by knittingor weaving with at least three applications of dispersed collagenfibrils.

The Herweck et al. patent, U.S. Pat. No. 5,197,976, discloses acontinuous one piece bifurcated graft having plural longitudinallyparallel tube structures which are attached to one another over at leasta portion of their longitudinal exteriors. The tube structures can bemanually separated to form a branched tubular structure. The prosthesisis manufactured by paste forming and stretching and/or expanding highlycrystalline unsintered polytetrafluoroethylene (PTFE). Paste formingincludes mixing the PTFE resin with a lubricant, such as mineralspirits, and then forming the resin by extrusion into shaped articles.

Although all of the above-described one piece bifurcated grafts haveeliminated the problems of leakage and graft failure at the suture orjuncture site associated with two piece bifurcated grafts which jointogether two separate grafts to form the bifurcated graft, problemsstill exist with these one piece bifurcated grafts. For example, thepreviously described one piece bifurcated grafts do not include anintegral support structure to prevent the deformation, twisting orcollapse of the graft limbs. Further, the same problems with graftmigration that existed with straight tube grafts still exist with theone piece bifurcated grafts. Accordingly, there is a need for a stableand durable bifurcated vascular graft which is structured to prevent themigration of the graft and the deformation and obstruction of the bloodflow through the limbs of the bifurcated graft.

Endoluminal implantation is a common technique for implanting vasculargrafts. Typically, this procedure involves percutaneously inserting avascular graft or prosthesis by using a delivery catheter. This processeliminates the need for major surgical intervention thereby decreasingthe risks associated with vascular and arterial surgery. Variouscatheter delivery systems for prosthetic devices are described in theprior art.

For example, bifurcated vascular grafts have been created by combininggrafts with stents on delivery systems in order to secure the graft endsto the blood vessel thereby stabilizing the bifurcated graft. In U.S.Pat. No. 5,360,443 issued to Barone et al., a method for repairing anabdominal aortic aneurysm is described. The method comprises the stepsof (1) connecting an expandable and deformable tubular member, such as astent, to each of the tubular passageways of a bifurcated graft, (2)disposing the bifurcated graft and deformable tubular members within theaortic and iliac arteries, and (3) expanding and deforming eachdeformable tubular member with a catheter to secure each tubularpassageway of the bifurcated graft within the appropriate artery. Thisreference only discloses a catheter delivery method for deploying theaortic portion of the bifurcated graft. The same catheter is supposedlyused to also expand and secure the associated stents within the iliacarteries.

The Palmaz et al. patent, U.S. Pat. No. 5,316,023, describes a methodand apparatus for repairing an abdominal aortic aneurysm in an aorta atthe iliac arteries. This method includes the steps of connecting a firsttubular graft to a first deformable and expandable tubular member,connecting a second tubular graft to a second deformable and expandabletubular member, disposing the first tubular graft and first tubularmember upon a first catheter having an inflatable portion, disposing thesecond tubular graft and second tubular member upon a second catheterhaving an inflatable portion, intraluminally delivering the first andsecond tubular grafts, tubular members and catheters to the aorta anddisposing at least a portion of each tubular graft within the abdominalaortic aneurysm, and expanding the tubular members with the inflatablecatheters to secure them and at least a portion of their associatedtubular grafts within the aorta. This patent reference employs twoseparate unconnected straight grafts which are employed within an aortato form a bifurcated graft.

Further, U.S. Pat. No. 4,617,932 issued to Kornberg discloses a devicefor inserting a graft into an artery comprising a plurality of nestedtubes each having an upper and lower end. A first outer tube has a meansfor guiding and positioning an arm means at its upper end. The arm meansis movably attached to the upper end of another tube located inside ofthe first tube and extending above the first outer tube. The lower endsof the tubes are adaptable for fastening means and the inside tubeextends below the end of the first outer tube. Delivery and placement ofa bifurcated graft is illustrated. U.S. Pat. No. 5,522,883 issued toSlater et al. describes an endoprosthesis stent/graft deployment systemwhich includes a tubular delivery catheter, a radially expandableprosthesis positioned over the catheter, a removable endoprosthesissupport assembly located adjacent the catheter opening and having an armextending through the catheter which keeps the endoprosthesis in acompressed state, and a release mechanism insertable through thecatheter for removing the support assembly.

U.S. Pat. No. 5,104,399 issued to Lazarus also describes an artificialgraft and delivery method. The delivery system includes a capsule fortransporting the graft through the blood vessel, a tube connected to thevessel which extends exterior to the vessel for manipulation by a user,and a balloon catheter positioned within the tube. Finally, U.S. Pat.No. 5,489,295 issued to Piplani et al. discloses a bifurcated graft anda method and apparatus for deploying the bifurcated graft. The Piplaniet al. graft includes a main tubular body, first and second tubular legsjoined to the main tubular body in a bifurcation, a first expandableattachment means for anchoring the main body located adjacent theopening for the first body, and a second expandably attachment meanslocated adjacent the opening of the first tubular leg for anchoring thefirst tubular leg. The graft is intraluminally implanted using acatheter that is inserted into the aortic bifurcation through a firstiliac artery so that the first attachment means adjacent the opening ofthe main body can be anchored in the aorta and the second attachmentmeans adjacent the opening of the first tubular leg can be anchored inthe first iliac artery. The second tubular leg is deployed into thesecond iliac artery by using a pull line attached to the second tubularleg. The Piplani et al. patent also discloses a deployment deviceconsisting of a capsule catheter, a balloon catheter, and a separateexpandable spring attachment means.

The previously described deployment methods, systems and devices do notallow for a bifurcated graft which is fully supported withself-expandable stents to be delivered and implanted within an arterialbifurcation. A use of any of the previously described deployment devicesor systems to implant the structural supported bifurcated graft of thepresent invention would result in failure due to the inability of thosedevices and systems to deliver and anchor the second supported limbwithin the second iliac artery. The previously described methods andsystems simply do not allow for the delivery and implantation of abifurcated vascular graft whose three open ends are supported by stents.Accordingly, not only is there a need for a structurally supportedstable and durable bifurcated graft which is not susceptible tomigration and leaking, but there is also a need for a delivery apparatusand method for deploying and implanting such a bifurcated graft.

SUMMARY OF THE INVENTION

There is disclosed in accordance with one aspect of the presentinvention, a bifurcated endoluminal prosthesis. The prosthesis comprisesa proximal wire support section having a proximal end, a distal end, anda central lumen extending therethrough. A first wire branch section isprovided at the distal end of the proximal support, and a second wirebranch section is also provided at the distal end of the proximalsupport. At least the proximal support section and the first branchsection are formed from a single length of wire.

Preferably, the proximal support comprises at least two axially adjacenttubular segments, joined by a connector there between. The wire in eachsegment is formed into a series of proximal bends and a series of distalbends, creating a series of struts connecting the proximal bends anddistal bends to form a tubular segment wall. Preferably, the wiredecreases in cross-section from a relatively large cross-section in theproximal wire support section to a relatively small cross-section at thedistal end of at least one of the first and second wire branch sections.A tubular sheath, such as PTFE or Teflon, is supported on the wire cage.

In accordance with another aspect of the present invention, there isprovided a method of making a bifurcated endoluminal prosthesis. Themethod comprises the steps of providing a first length of wire, andforming the wire into two or more zig zag sections. Each zig zag sectionis separated by a crosslink. The formed wire is rolled about an axis toproduce a proximal tubular support section and a first distal tubularbranch. A second length of wire is formed into a tube, and attached tothe distal end of the proximal tubular support section to produce asecond distal tubular branch.

Preferably, the method further comprises the step of positioning atubular polymeric sleeve concentrically on at least a part of theprosthesis.

In accordance with a further aspect of the present invention, there isprovided a multi-zone endoluminal bifurcation prosthesis. The prosthesiscomprises a tubular wire support having a proximal end, a distal end anda central lumen extending therethrough. The wire support comprises atleast a first and a second axially adjacent tubular segments, joined bya connector extending therebetween, wherein the first tubular segmenthas a different radial strength than the second tubular segment. A firstand a second tubular wire branches are connected to the distal end ofthe support to produce a multi-zone endoluminal bifurcation prosthesis.

In accordance with a further aspect of the present invention, there isprovided a method of implanting a self-expandable tubular prosthesis atthe junction of a main vessel and first and second branch vessels. Themethod comprises the steps of advancing a delivery catheter distallythrough at least a portion of the first branch and into the main vessel,the catheter containing a prosthesis having a main section and first andsecond branch sections. A main sheath is distally advanced on thecatheter to deploy the main section of the prosthesis within the mainvessel. A first branch sheath is proximally retracted to deploy thefirst branch portion of the prosthesis within the first branch vessel. Asecond branch sheath is proximally retracted to deploy the second branchportion of the prosthesis within the second branch vessel.

Preferably, the proximally retracting a second branch sheath step isaccomplished by pulling a wire connected to the second branch sheath,and extending transluminally through the contralateral iliac artery. Inone application, the main vessel comprises the aorta, and the first andsecond branch vessels comprise iliac arteries.

In accordance with a further aspect of the present invention, there isprovided a method of deploying first and second iliac branches of aself-expandable prosthesis. The method comprises the steps ofpositioning the first and second iliac branches of the prosthesis withinthe first and second iliac arteries, respectively. The positioning stepis accomplished while the first and second iliac branches of theprosthesis are constrained by first and second respective retentionstructures.

The first retention structure is withdrawn from the first branch andtransluminally through the first iliac to permit the first branch toexpand. The second retention structure is withdrawn from the secondbranch and transluminally through the second iliac to permit the secondbranch to expand.

Preferably, the first and second branches of the prosthesis areconnected to a main trunk portion for implantation within the aorta. Themethod additionally comprises the step of advancing a main sheath todeploy the main portion of the prosthesis within the aorta. The order ofdeploying the first and second branches and main portion of theprosthesis can proceed in any sequence.

In one embodiment of the invention, the withdrawing the first retentionstructure step comprises withdrawing a tubular sheath from around thefirst branch. The withdrawing the first retention structure stepadditionally or alternatively comprises pulling a pull wiretransluminally positioned within the iliac.

In accordance with a further aspect of the present invention, there isprovided a deployment catheter for deploying a self-expandable grafthaving a main vessel portion and first and second branch portions. Thecatheter comprises an elongate flexible body, having a first sheath forcontaining the main vessel portion of the graft. A second sheath isprovided for containing the first branch portion of the graft, and athird sheath is provided for containing the second branch portion of thegraft. In one embodiment, the first sheath is axially distallydisplacable to deploy the main vessel portion of the graft. Preferably,a contra lateral pull wire is attached to the second sheath, for pullingthe sheath proximally through the contra lateral iliac to release thefirst branch portion of the graft.

In accordance with a further aspect of the present invention, there isprovided a combination of a deployment catheter and a bifurcation graft,the bifurcation graft having a main portion and first and second branchportions. The combination comprises an elongate flexible body, havingproximal and distal ends. The body extends through the main portion andfirst branch portion of the graft such that the main portion of thegraft is disposed distally of the first portion of the graft. A firstsheath on the body is provided for containing the first branch portion,and a second sheath is provided for containing the second branchportion.

In one embodiment, a pull wire is provided for pulling the second sheathproximally from the second branch portion. In addition, a main sheath ispreferably axially movably positioned on the body for containing themain portion of the graft.

In accordance with a further aspect of the present invention, there isprovided a method of deploying a bifurcation graft at a bifurcation sitein a vessel. The method comprises the steps of introducing a catheterhaving the bifurcation graft and at least one removable graft retentionstructure thereon through a first percutaneous puncture. The graft isdeployed at the site, and the catheter is thereafter removed through thefirst percutaneous puncture. The removable graft retention structure isthereafter removed through a second percutaneous puncture.

Further features and advantages of the present invention will becomeapparent to those of skill in the art in view of the disclosure herein,when considered together with the attached drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a bifurcated endoluminalvascular prosthesis in accordance with the present invention, positionedat the bifurcation between the abdominal aorta and the right and leftcommon iliac arteries.

FIG. 1A is an elevational view of the implanted graft taken along thelines 1 a-1 a of FIG. 1.

FIG. 2 is an exploded view of the bifurcated vascular prosthesis inaccordance with the present invention, showing a two-part selfexpandable wire support structure separated from an outer tubularsleeve.

FIG. 3 is a plan view of a formed wire useful for rolling about an axisinto an aortic trunk segment and an iliac branch segment supportstructure in accordance with the present invention.

FIG. 4 is an enlarged detail view of a portion of the formed wireillustrated in FIG. 3.

FIG. 5 is a detail view of a portion of the wire illustrated in FIG. 4.

FIG. 6 is an enlarged detail view of the region marked 6-6 in FIG. 2.

FIG. 7 is a side elevational cross section of a deployment catheter inaccordance with the present invention.

FIG. 8 is an enlarged side elevational view of the portion of thecatheter of FIG. 7 identified by the lines 8-8.

FIG. 8A is a cross-section taken along the lines 8 a -8 a in FIG. 8,with the graft omitted for clarity.

FIG. 8B is a cross-section taken along the lines 8 b-8 b of FIG. 8, withthe iliac branches of the graft omitted for clarity.

FIG. 9 is a schematic representation of the deployment catheter of thepresent invention positioned within the ipsalateral iliac and the aorta,with the contralateral guidewire positioned within the contralateraliliac.

FIG. 10 is a schematic representation as in FIG. 9, with the outersheath proximally retracted and the compressed iliac branches of thegraft moving into position within the iliac arteries.

FIG. 11 is a schematic representation as in FIG. 10, with the compressediliac branches of the graft within the iliac arteries, and the mainaortic trunk of the graft deployed within the aorta.

FIG. 12 is a schematic representation as in FIG. 11, with thecontralateral iliac branch of the graft deployed.

FIG. 13 is a schematic illustration as in FIG. 12, following deploymentof the ipsalateral branch of the graft.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, there is disclosed a schematic representation ofthe abdominal part of the aorta and its principal branches. Inparticular, the abdominal aorta 30 is characterized by a right renalartery 32 and left renal artery 34. The large terminal branches of theaorta are the right and left common iliac arteries 36 and 38. Additionalvessels (e.g., second lumbar, testicular, inferior mesenteric, middlesacral) have been omitted for simplification. An abdominal aorticaneurysm 40 is illustrated in the infrarenal portion of the diseasedaorta. Portions of the same aneurysm 40 or additional aneurysms extendinto a bifurcation region 42 and an iliac region 44 of the left commoniliac 38.

An expanded endoluminal vascular prosthesis 45, in accordance with thepresent invention, is illustrated spanning the aneurysms 40, 42 and 44.The endoluminal vascular prosthesis 45 includes a polymeric sleeve 47and a tubular wire support 46, which are illustrated in situ in FIG. 1.The sleeve 47 and wire support 46 are more readily visualized in theexploded view shown in FIG. 2. The endoluminal prosthesis 45 illustratedand described herein depicts an embodiment in which the polymeric sleeve47 is situated concentrically outside of the tubular wire support 46.However, other embodiments may include a sleeve situated insteadconcentrically inside the wire support or on both of the inside and theoutside of the wire support. Alternatively, the wire support may beembedded within a polymeric matrix which makes up the sleeve. Regardlessof whether the sleeve 47 is inside or outside the wire support 46, thesleeve may be attached to the wire support by any of a variety of means,including laser bonding, adhesives, clips, sutures, dipping or sprayingor others, depending upon the composition of the sleeve 47 and overallgraft design.

The polymeric sleeve 47 may be formed from any of a variety of syntheticpolymeric materials, or combinations thereof, including PTFE, PE, PET,Urethane, Dacron, nylon, polyester or woven textiles. Preferably, thesleeve material exhibits relatively low inherent elasticity, or lowelasticity out to the intended enlarged diameter of the wire cage 46.The sleeve material preferably has a thin profile, such as no largerthan about 0.002 inches to about 0.005 inches.

In a preferred embodiment of the invention, the material of sleeve 47 issufficiently porous to permit ingrowth of endothelial cells, therebyproviding more secure anchorage of the prosthesis and potentiallyreducing flow resistance, shear forces, and leakage of blood around theprosthesis. Porosity in polymeric sleeve materials may be estimated bymeasuring water permeability as a function of hydrostatic pressure,which will preferably range from about 3 to 6 psi.

The porosity characteristics of the polymeric sleeve 47 may be eitherhomogeneous throughout the axial length of the prosthesis 45, or mayvary according to the axial position along the prosthesis 45. Forexample, referring to FIGS. 1 and 2, different physical properties willbe called upon at different axial positions along the prosthesis 45 inuse. At least a proximal portion 55 and right and left distal portions59 of the prosthesis 45 will seat against the native vessel wall,proximally and distally of the aneurysm. In at least these proximal anddistal portions, the prosthesis preferably encourages endothelialgrowth, or, at least, permits endothelial growth to infiltrate portionsof the prosthesis in order to enhance anchoring and minimize leakage. Acentral portion of the prosthesis spans the aneurysm, and anchoring isless of an issue. Instead, minimizing blood flow through the prosthesiswall becomes a primary objective. Thus, in a central zone of theprosthesis 42, the polymeric sleeve 44 may either be nonporous, orprovided with pores which minimize or prevent leakage.

A multi-zoned prosthesis 45 may also be provided in accordance with thepresent invention by positioning a tubular sleeve 47 on a centralportion of the prosthesis, such that it spans the aneurysm to betreated, but leaving a proximal attachment zone 55 and distal attachmentzones 59 of the prosthesis 45 having exposed wires from the wire support46. In this embodiment, the exposed wires 46 are positioned in contactwith the vessel wall both proximally and distally of the aneurysm, suchthat the wire, over time, becomes embedded in cell growth on theinterior surface of the vessel wall.

In one embodiment of the prosthesis 45, the sleeve 47 and/or the wiresupport 46 is stepped or tapered, having a relatively larger expandeddiameter at the proximal end 50 compared to the distal ends 52. Thetapered design may allow the prosthesis to conform better to the naturaldecreasing distal cross section of the aorta and iliacs to reduce therisk of leakage and graft migration and potentially create better flowdynamics.

The tubular wire support 46 comprises a primary component 49 fortraversing the aorta and a first iliac, and a branch component 51 forextending into the second iliac. The primary component 49 is preferablyformed from a continuous single length of wire, throughout both theaorta trunk portion and the iliac branch portion. See FIGS. 2 and 3. Thewire support 46 is preferably formed in a plurality of discretesegments, connected together and oriented about a common axis. In FIG.3, Section A corresponds to the aorta trunk portion of the primarycomponent 49, and includes segments 1-5. Segments 6-8 (Section B)correspond to the iliac branch portion of the primary component 49.

Each pair of adjacent segments is connected by a connector 66 as will bediscussed. The connectors 66 collectively produce a generally axiallyextending backbone which adds axial strength to the prosthesis 45.Adjacent segments can be connected both by the backbone, as well as byother structures, including circumferentially extending sutures, solderjoints, wire loops and any of a variety of interlocking relationships.The suture can be made from any of a variety of biocompatible polymericmaterials or alloys, such as nylon, polypropylene, or stainless steel.

The segmented configuration of the tubular wire support 46 facilitates agreat deal of flexibility. Each segment, though joined to adjacentsegments, may be independently engineered to yield desired parameters.Each segment may range in axial length from about 0.3 to about 5 cm.Generally, the shorter their length the greater the radial strength. Theprimary component 49 of an endoluminal prosthesis may include from about2 to about 50 segments, preferably from about 8 to about 16 segments.

In general, each of the components of the tubular wire support 46 can bevaried considerably in diameter, length, and expansion coefficient,depending upon the intended application. For implantation within atypical adult, the aorta trunk portion (section A) of primary component49 will have a length within the range of from about 5 cm to about 12cm, and, typically within the range of from about 9 cm to about 10 cm.The unconstrained outside expanded diameter of the section A portion ofthe primary component 49 will typically be within the range of fromabout 20 mm to about 40 mm. The unconstrained expanded outside diameterof the section A portion of primary component 49 can be constant orsubstantially constant throughout the length of section A, or can betapered from a relatively larger diameter at the proximal end to arelatively smaller diameter at the bifurcation. In general, the diameterof the distal end of section A will be on the order of no more thanabout 95% and, preferably, no more than about 85% of the diameter of theproximal end of section A.

The right and left iliac portions, corresponding to section B on primarycomponent 49 and section C will typically be bilaterally symmetrical.Section C length will generally be within the range of from about 1 cmto about 5 cm, and section C diameter will typically be within the rangeof from about 10 mm to about 20 mm.

In addition to the flexibility and other functional benefits availablethrough employment of different length segments, further flexibility canbe achieved through adjustments in the number, angle, or configurationof the wire bends associated with the tubular support.

For example, referring to FIG. 2, the wire cage 46 is dividable into aproximal zone 55, a central zone 57 and a distal zone 59. As has beendiscussed, the wire cage 46 can be configured to taper from a relativelylarger diameter in the proximal zone 55 to a relatively smaller diameterin the distal zone 59. In addition, the wire cage 46 can have atransitional tapered and or stepped diameter within a given zone.

The cage 46 can also be provided with a proximal zone 55 and distal zone59 that have a larger relative unconstrained expanded diameter than theadjacent portions of central zone 57. This configuration may desirablyresist migration of the prosthesis within the vessel. The proximal zone55 and/or distal zone 59 can be left without an outer covering 47, withthe outer sleeve 47 covering only a sufficient portion of the centralzone 57 to span the aneurysm. This permits the proximal and distal zones55, 59 to be in direct contact with tissue proximally and distal to thelesion, which may facilitate endothelial cell growth.

In addition to having differing expanded diameters in different zones ofthe prosthesis 45, different zones can be provided with a differentradial expansion force, such as ranging from about 2 lbs to about 8 lbs.In one embodiment, the proximal zone 55 is provided with a greaterradial force than the central zone 57 and/or distal zone 59. The greaterradial force can be provided in any of a variety of manners discussedelsewhere herein, such as through the use of an additional one or two orthree or more proximal bends 60, distal bends 62 and wall sections 64compared to a central zone reference segment such as segment 4 or 5 inSection A (FIG. 3). Alternatively, additional spring force can beachieved in the proximal zone 55 through the use of the same number ofproximal bends 60 as in the rest of the prosthesis, but with a heaviergauge wire. Radial force in the end zones beyond the expanded diameterlimit of the central zone 57 can be achieved by tightening acircumferential suture such that the central zone 57 is retained undercompression even in the expanded configuration. By omitting acircumferential suture at the proximal end and/or distal end of theprosthesis, the proximal end and distal end will flair radiallyoutwardly to a fully expanded configuration.

The wire may be made from any of a variety of different alloys, such aselgiloy, nitinol or MP35N, or other alloys which include nickel,titanium, tantalum, or stainless steel, high Co—Cr alloys or othertemperature sensitive materials. For example, an alloy comprising Ni15%, Co 40%, Cr 20%, Mo 7% and balance Fe may be used. The tensilestrength of suitable wire is generally above about 300 K psi and oftenbetween about 300 and about 340 K psi for many embodiments. In oneembodiment, a Chromium-Nickel-Molybdenum alloy such as that marketedunder the name Conichrom (Fort Wayne Metals, Indiana) has a tensilestrength ranging from 300 to 320 K psi, elongation of 3.5-4.0% andbreaking load at approximately 80 lbs to 70 lbs. The wire may be treatedwith a plasma coating and be provided with or without additionalcoatings such as PTFE, Teflon, Perlyne, drugs, and others as will beunderstood by those of skill in the art.

In addition to segment length and bend configuration, discussed above,another determinant of radial strength is wire gauge. The radialstrength, measured at 50% of the collapsed profile, preferably rangesfrom about 2 lb to 8 lb, and generally from about 4 lb to about 5 lb. ormore. Preferred wire diameters in accordance with the present inventionrange from about 0.004 inches to about 0.020 inches. More preferably,the wire diameters range from about 0.006 inches to about 0.018 inches.In general, the greater the wire diameter, the greater the radialstrength for a given wire layout. Thus, the wire gauge can be varieddepending upon the application of the finished graft, in combinationwith/or separate from variation in other design parameters (such as thenumber of struts, or proximal bends 60 and distal bends 62 per segment),as will be discussed.

In one embodiment of the bifurcation graft, the wire gauge remainssubstantially constant throughout section A of the primary component 49and steps down to a second, smaller cross section throughout section Bof primary component 49. See, for example, FIG. 4.

A wire diameter of approximately 0.018 inches may be useful in the aortatrunk portion of a graft having four segments each having 2.5 cm lengthper segment, each segment having six struts intended for use in theaorta, while a smaller diameter such as 0.006 inches might be useful forsegments of the graft having 5 struts per segment intended for the iliacartery.

In one embodiment of the present invention, the wire diameter is taperedthroughout from the proximal to distal ends of the section A and/orsection B portions of the primary component 49. Alternatively, the wirediameter may be tapered incremental or stepped down, or stepped up,depending on the radial strength requirements of each particularclinical application. In one embodiment, intended for the abdominalaortic artery, the wire has a cross section of about 0.018 inches in theproximal zone 55 and the wire tapers down regularly or in one or moresteps to a diameter of about 0.006 inches in the distal zone 59 of thegraft 45. End point dimensions and rates of taper can be varied widely,within the spirit of the present invention, depending upon the desiredclinical performance.

In general, in the tapered or stepped wire embodiments, the diameter ofthe wire in the iliac branches is no more than about 80%, preferably nomore than about 50%, and optimally no more than about 35% of thediameter of the wire in the aortic trunk. This permits increasedflexibility of the graft in the region of the iliac branches, which hasbeen determined by the present inventors to be clinically desirable.

Referring to FIG. 3, there is illustrated a plan view of the singleformed wire used for rolling about a longitudinal axis to produce aprimary segment 49 having a five segment aorta section and a threesegment iliac section. The formed wire exhibits distinct segments, eachcorresponding to an individual tubular segment in the tubular support.Additional details of the wire cage layout and construction can be foundin copending U.S. patent application Ser. No. 09/034,689 entitledEndoluminal Vascular Prosthesis, filed Mar. 4, 1998, the disclosure ofwhich is incorporated in its entirety herein by reference.

Each segment has a repeating pattern of proximal bends 60 connected tocorresponding distal bends 62 by wall sections 64 which extend in agenerally zig zag configuration when the segment is radially expanded.Each segment is connected to the adjacent segment through a connector66, except at the terminal ends of the graft. The connector 66 in theillustrated embodiment comprises two wall sections 64 which connect aproximal bend 60 on a first segment with a distal bend 62 on a second,adjacent segment. The connector 66 may additionally be provided with aconnector bend 68, which may be used to impart increased radial strengthto the graft and/or provide a tie site for a circumferentially extendingsuture.

Referring to FIG. 4, there is shown an enlarged view of the wire supportillustrating a connector 66 portion between adjacent segments 54. In theembodiment shown in FIG. 4, a proximal bend 60 comprises about a 180degree arc, having a radial diameter ranging from about 0.009 to about0.070 inches, depending on wire diameter followed on either side of thebend by relatively short lengths of parallel wire spanning an axialdistance of d1. The parallel wires thereafter diverge outwardly from oneanother and form the strut sections 64, or the proximal half of aconnector 66. At the distal end of the strut sections 64, the wire formsa distal bend 62, preferably having identical characteristics as theproximal bend 60, except being concave in the opposite direction. Theaxial direction component of the distance between the apices of thecorresponding proximal and distal bends 60, 62 is referred to as (d₂)and represents the axial length of that segment. The total expandedangle defined by the bend 60 and the divergent strut sections 64 isrepresented by α. Upon compression to a collapsed state, such as whenthe graft is within the deployment catheter, the angle α is reduced toα′ in which adjacent strut sections 64 are parallel or near parallel toeach other. In the expanded configuration, α is generally within therange of from about 30° to about 45° for a segment having about 6proximal bends 60. The expanded circumferential distance between any twoadjacent distal bends 62 (or proximal bends 60) is defined as (s).

In general, the diameter of each proximal bend 60 or distal bend 62 iswithin the range of from about 0.009 inches to about 0.070 inchesdepending upon the wire diameter. Bend diameter is preferably as smallas possible for a given wire diameter and wire characteristics. As willbe appreciated by those of skill in the art, as the diameter is reducedto approach two times the cross section of the wire, the bend 60 or 62will exceed the elastic limit of the wire, and radial strength of thefinished segment will be lost. Determination of a minimum value for thebend diameter, in the context of a particular wire diameter and wirematerial, can be readily determined through routine experimentation bythose of skill in the art. Similarly, although at least some distance ofd1 is desired, from the apex to the first bend in the wall section 64,the distance d1 is preferably minimized within the desired radialstrength performance requirements. As d1 increases, it maydisadvantageously increase the collapsed (implantation) profile of thegraft.

As will be appreciated from FIGS. 3 and 4, the sum of the distances (s)in a plane transverse to the longitudinal axis of the finished graftwill correspond to the circumference of the finished graft in thatplane. For a given circumference, the number of proximal bends 60 ordistal bends 62 is thus directly related to the distance (s) in thecorresponding plane. Preferably, the finished graft in any singletransverse plane will have from about 3 to about 10 (s) dimensions,preferably from about 4 to about 8 (s) dimensions and, more preferably,about 5 or 6 (s) dimensions for an aortic application. Each (s)dimension corresponds to the distance between any two adjacent bends60-60 or 62-62 as will be apparent from the discussion herein. Eachsegment can thus be visualized as a series of triangles extendingcircumferentially around the axis of the graft, defined by a proximalbend 60 and two distal bends 62 or the reverse.

One consequence of the foregoing structure is illustrated in FIG. 1A. Across-section through the implanted graft shows that the graft will tendto assume more of a polygon than a circular configuration. The number offaces on the polygon is related to the number of proximal bends 60 ineach segment. This configuration advantageously increases the radialpressure at localized points around the circumference of the graft,which appears to resist axial migration of the expanded graft within thevessel.

By modifying wire support parameters (such as d₁, d₂, s, and alpha), themanufacturer enjoys tremendous design control with respect to the totalaxial length, axial and radial flexibility, radial force and expansionratios, and consequently prosthesis performance. For example, anincrease in the diameter of the bend 60 or 62 translates directly intoan increased collapsed profile since the circumference of the collapsedprofile can be no smaller than the sum of the bend diameters in a giventransverse plane. Similarly, an increase in the number of proximal bends60 in a given segment may increase radial strength, but will similarlyincrease the collapsed profile. Since the primary radial force comesfrom the proximal bends 60 and distal bends 62, the wall sections 64 actas a lever arm for translating that force into radial strength. As aconsequence, decreasing the length of strut sections 64 for a givennumber of proximal bends 60 will increase the radial strength of thesegment but call for additional segments to maintain overall graftlength. Where a minimal entry profile is desired, radial strength isbest accomplished by decreasing the length of wall sections 64 ratherthan increasing the number of proximal bends 60. On the other hand,increasing the number of (shorter) segments in a given overall lengthgraft will increase the degree of axial shortening upon radial expansionof the graft. Thus, in an embodiment where axial shortening is to beavoided, increased radial strength may be optimized through selection ofwire material or wire gauge and other parameters, while minimizing thenumber of total segments in the graft. Other geometry consequences ofthe present invention will be apparent to those of skill in the art inview of the disclosure herein.

In one embodiment of the type illustrated in FIGS. 2 and 3, the benddiameter is about 2.0 mm±1 mm for a 0.018 inch wire diameter; d₁ isabout 3 mm±1 mm; d₂ is about 20 mm±1 mm; d₂+a (b) is about 23 mm±1 mm; gis about 17 mm,±1 mm; and a is about 3 mm±1 mm. Specific dimensions forall of the foregoing variables can be varied considerably, dependingupon the desired wire configuration, in view of the disclosure herein.

Each pair of adjacent segments may be joined by crosslinking of thecorresponding proximal and distal bends. See, for example, FIG. 6. Thus,a proximal bend 60 from a distal adjacent segment is connected to thecorresponding distal bend 62 of a proximal adjacent segment therebycoupling the proximal and distal segment. The connection betweencorresponding proximal bends 60 and distal bends 62 can be accomplishedin any of a variety of ways as will be apparent to those of skill in theart in view of the disclosure herein. For example, the connection may beaccomplished through the use of a link. The link may be a loop of metalsuch as stainless steel, a suture, a welded joint or other type ofconnection. Preferably, the link comprises a metal loop or ring whichpermits pivotable movement of a proximal segment with respect to theadjacent distal segment.

In one example of an endoluminal vascular prosthesis in accordance withthe present invention, a link may be provided at each pair ofcorresponding bends 60, 62, such that six links 72 exist in a planetransverse to the longitudinal axis of the graft at the interfacebetween the proximal segment and the distal segment in a graft havingsix bends 60, 62 in adjoining planes. Alternatively, links can beprovided at less than all of the corresponding bends, such as at everyother bend, every third bend, or only on opposing sides of the graft.The distribution of the links 72 in any given embodiment can be selectedto optimize the desired flexibility characteristics and otherperformance criteria in a given design.

Preferably, each link 72 provides a pivotable linkage, such as isaccomplished using a metal loop or a suture for link 72. The use ofmoveable links 72 in combination with the multisegment structure of thepresent invention has been determined to optimize patency of the centrallumen through the graft throughout a wide variety of angularrelationships of the iliac branches to the main trunk, as well as toaccommodate nonlinear configurations of the aorta and iliacs. Ingeneral, the abdominal aortic anatomy varies considerably from patientto patient, requiring the implanted graft to assume any of a widevariety of different angular orientations. In addition, the path of theaorta as well as the angle of the iliacs is susceptible to change overtime following implantation of the graft. The multisegment constructionof the present invention enables the graft to change with thesurrounding anatomy, while maintaining maximum patency throughout.

The segmented, linked graft of the present invention is also able to beformed into a nonlinear configuration, and retain its form withoutcompromising patency of the central lumen. Thus, the cage constructionof the present invention permits both improved anatomical conformancewith a wide variety of different abdominal aortic anatomies at the timeof implantation as well as improved conformance to the anatomy followingpost implantation changes which are known to occur. The graft of thepresent invention thus minimizes late leakage which can otherwise occurdue to a poor conformance between the graft and the changing aortic andiliac configurations.

In the illustrated embodiment, section A is intended for deploymentwithin the aorta whereas section B is intended to be deployed within afirst iliac. Thus, section B will preferably have a smaller expandeddiameter than section A. This may be accomplished by providing fewerproximal and distal bends 60, 62 per segment in section B or in othermanners as will be apparent to those of skill in the art in view of thedisclosure herein. In the illustrated embodiment, section B has onefewer proximal bend 60 per segment than does each segment in section A.This facilitates wrapping of the wire into a tubular prosthesis cagesuch as that illustrated in FIG. 2, so that the iliac branch has asmaller diameter than the aorta branch. At the bifurcation, an openingremains for connection of the second iliac branch. The second branch ispreferably formed from a section of wire in accordance with the generalprinciples discussed above, and in a manner that produces a similarlydimensioned wire cage as that produced by section B. The second iliacbranch (section C) may be attached at the bifurcation to section Aand/or section B in any of a variety of manners, to provide a securejunction therebetween. In one embodiment, one or two of the proximalbends 60 on section C will be secured to the corresponding distal bends62 on the distal most segment of section A. Attachment may beaccomplished such as through the use of a circumferentially threadedsuture, through links as has been discussed previously, throughsoldering or other attachment means. The attachment means will beinfluenced by the desirable flexibility of the graft at the bifurcation,which will in turn be influenced by the method of deployment of thevascular graft as will be apparent to those of skill in the art in viewof the disclosure herein.

The collapsed prosthesis in accordance with the present invention has adiameter in the range of about 2 to about 10 mm. Preferably, the maximumdiameter of the collapsed prosthesis is in the range of about 3 to 6 mm(12 to 18 French). More particularly, the delivery catheter includingthe prosthesis will be 19 F, 16 F, 14 F, or smaller. After deployment,the expanded endoluminal vascular prosthesis has radially self-expandedto a diameter anywhere in the range of about 20 to 40 mm, correspondingto expansion ratios of about 1:2 to 1:20. In a preferred embodiment, theexpansion ratios range from about 1:4 to 1:8, more preferably from about1:4 to 1:6.

The self expandable bifurcation graft of the present invention can bedeployed at a treatment site in accordance with any of a variety oftechniques as will be apparent to those of skill in the art. One suchtechnique is disclosed in copending patent application Ser. No.08/802,478 entitled Bifurcated Vascular Graft and Method and Apparatusfor Deploying Same, filed Feb. 20, 1997, the disclosure of which isincorporated in its entirety herein by reference.

A partial cross sectional side elevational view of one deploymentapparatus 120 in accordance with the present invention is shown in FIG.7. The deployment apparatus 120 comprises an elongate flexiblemulticomponent tubular body 122 having a proximal end 124 and a distalend 126. The tubular body 122 and other components of this system can bemanufactured in accordance with any of a variety of techniques wellknown in the catheter manufacturing field. Suitable materials anddimensions can be readily selected taking into account the naturalanatomical dimensions in the iliacs and aorta, together with thedimensions of the desired percutaneous access site.

The elongate flexible tubular body 122 comprises an outer sheath 128which is axially movably positioned upon an intermediate tube 130. Acentral tubular core 132 is axially movably positioned within theintermediate tube 130. In one embodiment, the outer tubular sheathcomprises extruded PTFE, having an outside diameter of about 0.250″ andan inside diameter of about 0.230″. The tubular sheath 128 is providedat its proximal end with a manifold 134, having a hemostatic valve 136thereon and access ports such as for the infusion of drugs or contrastmedia as will be understood by those of skill in the art.

The outer tubular sheath 128 has an axial length within the range offrom about 40″ to about 55″, and, in one embodiment of the deploymentdevice 120 having an overall length of 110 cm, the axial length of theouter tubular sheath 128 is about 52 cm and the outside diameter is nomore than about 0.250″. Thus, the distal end of the tubular sheath 128is located at least about 16 cm proximally of the distal end 126 of thedeployment catheter 120 in stent loaded configuration.

As can be seen from FIGS. 7 and 8, proximal retraction of the outersheath 128 with respect to the intermediate tube 130 will expose thecompressed iliac branches of the graft, as will be discussed in moredetail below.

A distal segment of the deployment catheter 120 comprises an outertubular housing 138, which terminates distally in an elongate flexibletapered distal tip 140. The distal housing 138 and tip 140 are axiallyimmovably connected to the central core 132 at a connection 142.

The distal tip 140 preferably tapers from an outside diameter of about0.225″ at its proximal end to an outside diameter of about 0.070″ at thedistal end thereof. The overall length of the distal tip 140 in oneembodiment of the deployment catheter 120 is about 3″. However, thelength and rate of taper of the distal tip 140 can be varied dependingupon the desired trackability and flexibility characteristics. Thedistal end of the housing 138 is secured to the proximal end of thedistal tip 140 such as by heat shrinking, thermal bonding, adhesivebonding, and/or any of a variety of other securing techniques known inthe art. The proximal end of distal tip 140 is preferably also directlyor indirectly connected to the central core 132 such as by a frictionfit and/or adhesive bonding.

In at least the distal section of the catheter, the central core 132preferably comprises a length of hypodermic needle tubing. Thehypodermic needle tubing may extend throughout the length catheter tothe proximal end thereof, or may be secured to the distal end of aproximal extrusion as illustrated for example in FIG. 8. A centralguidewire lumen 144 extends throughout the length of the tubular centralcore 132, having a distal exit port 146 and a proximal access port 148as will be understood by those of skill in the art.

Referring to FIGS. 7 and 8, a bifurcated endoluminal graft 150 isillustrated in a compressed configuration within the deployment catheter120. The graft 150 comprises a distal aortic section 152, a proximalipsalateral iliac portion 154, and a proximal contralateral iliacportion 156. The aortic trunk portion 152 of the graft 150 is containedwithin the tubular housing 138. Distal axial advancement of the centraltubular core 132 will cause the distal tip 140 and housing 138 toadvance distally with respect to the graft 150, thereby permitting theaortic trunk portion 152 of the graft 150 to expand to its larger,unconstrained diameter. Distal travel of the graft 150 is prevented by adistal stop 158 which is axially immovably connected to the intermediatetube 130. Distal stop 158 may comprise any of a variety of structures,such as an annular flange or component which is adhered to, bonded to orintregally formed with a tubular extension 160 of the intermediate tube132. Tubular extension 160 is axially movably positioned over thehypotube central core 132.

The tubular extension 160 extends axially throughout the length of thegraft 150. At the proximal end of the graft 150, a step 159 axiallyimmovably connects the tubular extension 160 to the intermediate tube130. In addition, the step 159 provides a proximal stop surface toprevent proximal travel of the graft 150 on the catheter 120. Thefunction of step 159 can be accomplished through any of a variety ofstructures as will be apparent to those of skill in the art in view ofthe disclosure herein. For example, the step 159 may comprise an annularring or spacer which receives the tubular extension 160 at a centralaperture therethrough, and fits within the distal end of theintermediate tube 130. Alternatively, the intermediate tube 130 can bereduced in diameter through a generally conical section or shoulder tothe diameter of tubular extension 160.

Proximal retraction of the outer sheath 128 will release the iliacbranches 154 and 156 of the graft 150. The iliac branches 154 and 156will remain compressed, within a first (ipsalateral) tubular sheath 162and a second (contralateral) tubular sheath 164. The first tubularsheath 162 is configured to restrain the ipsalateral branch of the graft150 in the constrained configuration, for implantation at the treatmentsite. The first tubular sheath 162 is adapted to be axially proximallyremoved from the iliac branch, thereby permitting the branch to expandto its implanted configuration. In one embodiment, the first tubularsheath 162 comprises a thin walled PTFE extrusion having an outsidediameter of about 0.215″ and an axial length of about 7.5 cm. A proximalend of the tubular sheath 162 is necked down such as by heat shrinkingto secure the first tubular sheath 162 to the tubular extension 160. Inthis manner, proximal withdrawal of the intermediate tube 130 will inturn proximally advance the first tubular sheath 162 relative to thegraft 150, thereby deploying the self expandable iliac branch of thegraft 150.

The second tubular sheath 164 is secured to the contralateral guidewire166, which extends outside of the tubular body 122 at a point 168, suchas may be conveniently provided at the junction between the outertubular sheath 128 and the distal housing 138. The second tubular sheath164 is adapted to restrain the contralateral branch of the graft 150 inthe reduced profile. In one embodiment of the invention, the secondtubular sheath 164 has an outside diameter of about 0.215″ and an axiallength of about 7.5 cm. The second tubular sheath 164 can have asignificantly smaller cross section than the first tubular sheath 162,due to the presence of the tubular core 132 and intermediate tube 130within the first iliac branch 154.

The second tubular sheath 164 is secured at its proximal end to a distalend of the contralateral guidewire 166. This may be accomplished throughany of a variety of securing techniques, such as heat shrinking,adhesives, mechanical interfit and the like. In one embodiment, theguidewire is provided with a knot or other diameter enlarging structureto provide an interference fit with the proximal end of the secondtubular sheath 156, and the proximal end of the second tubular sheath156 is heat shrunk and/or bonded in the area of the knot to provide asecure connection. Any of a variety of other techniques for providing asecure connection between the contralateral guidewire 166 and tubularsheath 156 can readily be used in the context of the present inventionas will be apparent to those of skill in the art in view of thedisclosure herein. The contralateral guidewire 166 can comprise any of avariety of structures, including polymeric monofilament materials,braided or woven materials, metal ribbon or wire, or conventionalguidewires as are well known in the art.

In use, the free end of the contralateral guidewire 166 ispercutaneously inserted into the arterial system, such as at a firstpuncture in a femoral artery. The contralateral guidewire is advancedthrough the corresponding iliac towards the aorta, and crossed over intothe contralateral iliac in accordance with cross over techniques whichare well known in the art. The contralateral guidewire is then advanceddistally down the contralateral iliac where it exits the body at asecond percutaneous puncture site.

The deployment catheter 120 is thereafter percutaneously inserted intothe first puncture, and advanced along a guidewire (e.g. 0.035 inch)through the ipsalateral iliac and into the aorta. As the deploymentcatheter 120 is transluminally advanced, slack produced in thecontralateral guidewire 166 is taken up by proximally withdrawing theguidewire 166 from the second percutaneous access site. In this manner,the deployment catheter 120 is positioned in the manner generallyillustrated in FIG. 9.

Referring to FIG. 10, the outer sheath 128 is proximally withdrawn whilemaintaining the axial position of the overall deployment catheter 120,thereby releasing the first and second iliac branches of the graft 150.Proximal advancement of the deployment catheter 120 and contralateralguidewire 166 can then be accomplished, to position the iliac branchesof the graft 150 within the iliac arteries as illustrated.

Referring to FIG. 11, the central core 132 is distally advanced therebydistally advancing the distal housing 138 as has been discussed. Thisexposes the aortic trunk of the graft 150, which deploys into its fullyexpanded configuration within the aorta. As illustrated in FIG. 12, thecontralateral guidewire 166 is thereafter proximally withdrawn, therebyby proximally withdrawing the second sheath 164 from the contralateraliliac branch 156 of the graft 150. The contralateral branch 156 of thegraft 150 thereafter self expands to fit within the iliac artery. Theguidewire 166 and sheath 164 may thereafter be proximally withdrawn andremoved from the patient, by way of the second percutaneous access site.

Thereafter, the deployment catheter 120 may be proximally withdrawn torelease the ipsalateral branch 154 of the graft 150 from the firsttubular sheath 162. Following deployment of the ipsalateral branch 154of the prosthesis 150, a central lumen through the aortic trunk 152 andipsalateral branch 154 is sufficiently large to permit proximalretraction of the deployment catheter 120 through the deployedbifurcated graft 150. The deployment catheter 120 may thereafter beproximally withdrawn from the patient by way of the first percutaneousaccess site.

While the foregoing embodiments of the present invention have been setforth in detail for the purposes of making a complete disclosure of theinvention, the above-described embodiments of the invention are intendedto be illustrative only. Numerous alternative embodiments may be devisedby those skilled in the art without departing from the spirit and scopeof the following claims.

1. A bifurcated endoluminal prosthesis, comprising: a proximal wiresupport section having a proximal end, a distal end and a central lumenextending therethrough; a first wire branch section at the distal end ofthe proximal support; and a second wire branch section at the distal endof the proximal support; wherein at least the proximal support sectionand the first branch section are formed from a single length of wire.